// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Maxim Integrated MAX5481-MAX5484 digital potentiometer driver
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* Copyright 2016 Rockwell Collins
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*
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* Datasheet:
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* https://datasheets.maximintegrated.com/en/ds/MAX5481-MAX5484.pdf
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*/
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#include <linux/iio/iio.h>
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#include <linux/iio/sysfs.h>
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#include <linux/module.h>
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#include <linux/mod_devicetable.h>
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#include <linux/property.h>
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#include <linux/spi/spi.h>
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/* write wiper reg */
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#define MAX5481_WRITE_WIPER (0 << 4)
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/* copy wiper reg to NV reg */
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#define MAX5481_COPY_AB_TO_NV (2 << 4)
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/* copy NV reg to wiper reg */
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#define MAX5481_COPY_NV_TO_AB (3 << 4)
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#define MAX5481_MAX_POS 1023
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enum max5481_variant {
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max5481,
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max5482,
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max5483,
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max5484,
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};
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struct max5481_cfg {
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int kohms;
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};
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static const struct max5481_cfg max5481_cfg[] = {
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[max5481] = { .kohms = 10, },
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[max5482] = { .kohms = 50, },
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[max5483] = { .kohms = 10, },
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[max5484] = { .kohms = 50, },
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};
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struct max5481_data {
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struct spi_device *spi;
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const struct max5481_cfg *cfg;
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u8 msg[3] ____cacheline_aligned;
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};
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#define MAX5481_CHANNEL { \
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.type = IIO_RESISTANCE, \
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.indexed = 1, \
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.output = 1, \
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.channel = 0, \
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.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
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.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
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}
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static const struct iio_chan_spec max5481_channels[] = {
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MAX5481_CHANNEL,
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};
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static int max5481_write_cmd(struct max5481_data *data, u8 cmd, u16 val)
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{
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struct spi_device *spi = data->spi;
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data->msg[0] = cmd;
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switch (cmd) {
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case MAX5481_WRITE_WIPER:
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data->msg[1] = val >> 2;
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data->msg[2] = (val & 0x3) << 6;
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return spi_write(spi, data->msg, 3);
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case MAX5481_COPY_AB_TO_NV:
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case MAX5481_COPY_NV_TO_AB:
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return spi_write(spi, data->msg, 1);
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default:
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return -EIO;
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}
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}
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static int max5481_read_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan,
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int *val, int *val2, long mask)
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{
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struct max5481_data *data = iio_priv(indio_dev);
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if (mask != IIO_CHAN_INFO_SCALE)
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return -EINVAL;
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*val = 1000 * data->cfg->kohms;
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*val2 = MAX5481_MAX_POS;
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return IIO_VAL_FRACTIONAL;
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}
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static int max5481_write_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan,
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int val, int val2, long mask)
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{
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struct max5481_data *data = iio_priv(indio_dev);
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if (mask != IIO_CHAN_INFO_RAW)
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return -EINVAL;
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if (val < 0 || val > MAX5481_MAX_POS)
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return -EINVAL;
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return max5481_write_cmd(data, MAX5481_WRITE_WIPER, val);
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}
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static const struct iio_info max5481_info = {
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.read_raw = max5481_read_raw,
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.write_raw = max5481_write_raw,
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};
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static const struct of_device_id max5481_match[] = {
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{ .compatible = "maxim,max5481", .data = &max5481_cfg[max5481] },
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{ .compatible = "maxim,max5482", .data = &max5481_cfg[max5482] },
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{ .compatible = "maxim,max5483", .data = &max5481_cfg[max5483] },
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{ .compatible = "maxim,max5484", .data = &max5481_cfg[max5484] },
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{ }
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};
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MODULE_DEVICE_TABLE(of, max5481_match);
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static int max5481_probe(struct spi_device *spi)
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{
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struct iio_dev *indio_dev;
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struct max5481_data *data;
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const struct spi_device_id *id = spi_get_device_id(spi);
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int ret;
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indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
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if (!indio_dev)
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return -ENOMEM;
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dev_set_drvdata(&spi->dev, indio_dev);
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data = iio_priv(indio_dev);
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data->spi = spi;
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data->cfg = device_get_match_data(&spi->dev);
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if (!data->cfg)
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data->cfg = &max5481_cfg[id->driver_data];
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indio_dev->name = id->name;
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indio_dev->modes = INDIO_DIRECT_MODE;
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/* variant specific configuration */
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indio_dev->info = &max5481_info;
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indio_dev->channels = max5481_channels;
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indio_dev->num_channels = ARRAY_SIZE(max5481_channels);
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/* restore wiper from NV */
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ret = max5481_write_cmd(data, MAX5481_COPY_NV_TO_AB, 0);
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if (ret < 0)
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return ret;
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return iio_device_register(indio_dev);
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}
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static int max5481_remove(struct spi_device *spi)
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{
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struct iio_dev *indio_dev = dev_get_drvdata(&spi->dev);
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struct max5481_data *data = iio_priv(indio_dev);
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iio_device_unregister(indio_dev);
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/* save wiper reg to NV reg */
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return max5481_write_cmd(data, MAX5481_COPY_AB_TO_NV, 0);
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}
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static const struct spi_device_id max5481_id_table[] = {
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{ "max5481", max5481 },
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{ "max5482", max5482 },
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{ "max5483", max5483 },
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{ "max5484", max5484 },
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{ }
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};
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MODULE_DEVICE_TABLE(spi, max5481_id_table);
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static struct spi_driver max5481_driver = {
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.driver = {
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.name = "max5481",
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.of_match_table = max5481_match,
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},
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.probe = max5481_probe,
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.remove = max5481_remove,
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.id_table = max5481_id_table,
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};
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module_spi_driver(max5481_driver);
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MODULE_AUTHOR("Maury Anderson <maury.anderson@rockwellcollins.com>");
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MODULE_DESCRIPTION("max5481 SPI driver");
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MODULE_LICENSE("GPL v2");
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